Conventionally, there has been proposed a technology in which houses are grouped and power supplied to the houses is cooperatively adjusted therebetween within the group. Patent Document 1 discloses a technology for distributing power supplied from an electric company, wherein a power supply control device is provided between the entire houses included in a group and a power system through which the electric company supplies power. Further, the power supply control device monitors an amount of electric power demand in the houses to adjust the power supply-demand balance.
In the technology disclosed in Patent Document 1, it is assumed that a distributed power source such as a micro gas turbine power generation device, a photovoltaic power generation device, a wind power generation device and a fuel cell is provided in at least some of the houses in the group. Thus, the power supply control device has a function of collectively selling surplus power generated by the distributed power source to the electric company, and a function of collectively purchasing insufficient power of the houses from the electric company. Further, if the power to be supplied to the entire houses of the group is insufficient, the power supply control device collectively receives power from the electric company and distributes the power to each of the power demand houses.
That is, since the power supply control device has a function of distributing the power of the distributed power source provided in a group to the houses of the group, it is possible to reduce the amount of power supplied from the electric company.
On the other hand, in Patent Document 2, there has been proposed a photovoltaic power generating and supplying system for grid connection including a plurality of power generation load units each having a solar cell, a DC to AC conversion unit and an AC load, and a single control center including a common storage cell and a storage control unit, the power generation load units connecting the single control center. Further, the control center is connected to a power system provided by an electric company. The DC to AC conversion unit has a function of converting a DC power generated by the solar cell into an AC power and supplying the AC power to the AC load and the storage control unit.
In the technology disclosed in Patent Document 2, the control center monitors the excess or deficiency of power in each of the power generation load units, stores power in the common storage cell when there is surplus power, and feeds power to the power generation load units from the common storage cell when the power is insufficient. Further, the control center detects the amount of the power stored in the common storage cell, receives power from the power system when the power stored is insufficient, and causes a reverse power flow to the power system from the common storage cell when there is a surplus in the power stored.
In the technology disclosed in Patent Document 2, the solar cell corresponds to the distributed power source, and the power generation load units can be regarded as the houses on the power demand side. Further, the houses connected to the control center can be regarded as a group. In other words, in the configuration described in Patent Document 2, the distributed power source is provided in the group including the power demand houses, and the power supply from the power system provided by the electric company and the reverse power flow to the power system are collectively controlled by the center device, in the same way as the configuration described in Patent Document 1.
[Patent Document 1] Japanese Patent Application Publication No. 2002-10499
[Patent Document 1] Japanese Patent Application Publication No. 2002-233077
As mentioned above, by using the technologies described in Patent Documents 1 and 2, the power generated by the distributed power source can be used in the power demand houses of the group, and there is a connection point for grid connection of the power system provided by the electric company and the power generated by the distributed power source.
Further, in the configurations described in Patent Documents 1 and 2, since the electric company cannot notice the amount of the power generated by the distributed power source or the amount of the power consumed in each house, it cannot determine an electricity charge of each house. In other words, the amount of the power supplied from the power system and the amount of the power reversely flowing to the power system are perceived only by the power supply control device or the control center relaying between the power system provided by the electric company and the power demand houses.
In the technologies described in Patent Documents 1 and 2, however, it is possible to perceive the amount of the power supplied to the power supply control device or the control center and the amount of the power reversely flowing from the power supply control device or the control center. Accordingly, the electric company can collect electricity charges based thereon without providing a power meter in each house.
On the other hand, in the power demand houses, the more the amount of the power used, the larger the amount of the power accommodated by other house. Therefore, if each house individually makes a contract with the electric company, it is impossible to employ the technologies of Patent Documents 1 and 2.